Sensory Mechanisms Limiting Connectivity At Different Scales Jelle ATEMA*1, Gabriele GERLACH2, Vanessa MILLER-SIMS3, Michael KINGSFORD4 1 Biology, Boston University, Boston, MA, 2University of Oldenburg, Oldenburg, Germany, 3University of Southern California, Los Angeles, CA, 4James Cook University, Townsville, Australia International Coral Reef Symposium Fort Lauderdale FL. July 2008 Mini-symposium Reef Connectivity (#14) Jelle Atema, Gabriele Gerlach, Vanessa Miller-Sims, Michael Kingsford Presenter: Jelle Atema, Boston University Sensory mechanisms limiting connectivity at different scales Evidence from different coral reef fish species shows that settling larvae prefer the odor of the reef where they were captured. Indirect evidence shows that this is most likely also their natal reef, where odor imprinting occurred at hatching as demonstrated in Amphiprion sp. imprinting on anemones. When settling, different species appear to use this odor information differently resulting in different connectivity scales. The cardinal fish O. doederleini shows limited larval dispersal and strong homing. Genetic data show that it does not often survive to maturity in non-natal reefs even as close as a few km away. Behavioral experiments show that settlers from foreign reefs face severe conspecific competition, reflecting perhaps a limitation on settlement sites. Such post settlement competition would exert strong selection pressure for homing. In habituation tests they show persistent home odor preference. Other cardinal fishes behave similarly in odor choice tests. In contrast, the damsel fish P. coelestis can settle “abroad” and genetics shows it does so at a spatial scale of 20-100 km. This relaxes selection pressure for homing and facilitates the wider dispersal. Settlers still show evidence for imprinting on reef odor but their odor preference is less persistent. They may use their knowledge of home odor to later recognize any reef. This species settles on outer reef slopes where competition for settlement sites may be less severe. Finally, the damsel fish A. polyacanthus guards its larvae, which do not have a pelagic dispersal phase and do not show home odor preference in choice tests. Their behavior appears to allow for juvenile integration into adult habitat with very limited local dispersal. In ocean environments it is important to understand the local hydrography and the spatial-temporal scale of mixing water masses, identifiable by the odor of their origin.
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